A distributed energy system typically involves the generation of energy using a number of low- to mid-capacity power generation sites in lieu of one centrally located, high-capacity plant. Energy can be generated with a distributed energy system using, for example, hydraulic turbines, micro-turbines, photovoltaic devices, fuel cells, and wind-powered generators.
Because distributed energy systems can integrate renewable energy resources such as wind and solar power, they are thought by many experts to be a possible solution to rising oil and natural gas prices. Additionally, because wind power and solar power tend to be “cleaner” sources of energy, distributed energy systems are also thought by many experts to offer a solution to environmental problems arising from the generation of power with more conventional systems such as fossil-fuel-based systems.
One aspect of distributed energy systems not yet adequately addressed is that of a power electronics topology for such system. Although cascaded H-bridge multilevel converters have been proposed for interfacing renewable energy resources, conventional electrical topologies using such converters are thought to have certain inherent limitations. One limitation is that the integrated energy sources typically must be of the same type. Another limitation is that the H-bridges of the conventional cascaded H-bridge multilevel converters generally must maintain a constant DC voltage. These limitations can be a significant impediment to developing hybrid energy system applications, especially those utilizing variable or stochastic energy sources such as wind and solar power.